Filtering device, in particular for the air to be supplied to a fuel cell

ABSTRACT

A filtering device features a carrier medium and activated carbon as adsorbent which is immobilized due to the addition of adhesive.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 USC 119 of foreignapplication DE 102012013744.3 filed in Germany on Jul. 12, 2012, andwhich is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The invention relates to a filtering device, in particular for the airto be supplied to a fuel cell or for filtering pesticides.

PRIOR ART

The U.S. Pat. No. 7,758,674 B2 describes a filtering device for the airto be supplied to a fuel cell. With the aid of the filtering device theair can be cleaned from contaminant particles as well as from chemicalimpurities. For this purpose, the filtering device features a filterfleece on which the contaminant particles are separated as well as astratum of activated carbon, which serves as adsorbent for theadsorption of gaseous elements in the air.

SUMMARY OF THE INVENTION

The object of the invention is to design a filtering device, whichfeatures activated carbon as adsorbent, with simple measures in such away that even over a long period of use a good degree of efficiency isensured.

The filtering device according to the invention can be used to filterimpurities chemically from a gas flow by way of adsorption. Thefiltering device is, for example, used for cleaning the air to besupplied to a fuel cell by adsorbing gaseous impurities in the air. Thefiltering device can also be used for filtering pesticides. Thefiltering device features, on the one hand, a carrier medium and, on theother hand, activated carbon as adsorbent which is according to theinvention immobilized due to the addition of adhesive. This will make itpossible to realize activated carbon strata which maintain theirstructure unlike activated carbon bulks even under mechanical stress andlong periods of use; displacements and local compressions of theactivated carbon particles which could lead to an impairment of theadsorption performance are avoided. Impairments of the adsorptionperformance are based, for example, on local faults in the bulk whichmay cause leakages. Due to the immobilization of the activated carbonparticles in this embodiment according to the invention, the airpermeability is higher than in bulks with activated carbon particles ofcomparable grain diameter. Furthermore, the immobilization of theactivated carbon particles has the advantage that various geometries ofthe filtering device or the layers of the carrier medium and theactivated carbon can be generated. Rectangular as well asnon-rectangular cuts can be considered.

The immobilization of the activated carbon particles in the activatedcarbon stratum is obtained by adding adhesive, the adhesive threads ofwhich adhere to the surface of the activated carbon particles andconnect various activated carbon particles, however, without impairingthe adsorption performance of the activated carbon. A reactive adhesive,for example, can be considered as adhesive, e.g. on the basis ofpolyurethane or silane. A thermoplastic adhesive, which is, for example,manufactured on the basis of polyolefins, is also possible.

The carrier medium is carrier of the activated carbon or abuts at leastagainst the activated carbon stratum. The carrier medium is, forexample, designed as carrier layer and/or carrier stratum, which ensuresa mechanical filtration of particulate contamination of the gaseousfluid to be cleaned, if required. In this case, the carrier mediumforms, for example, a carrier or filter fleece, on which contaminantparticles can be separated, The filter fleece consists, for example, ofpolyester, polypropylene, 4, polyacrylonitrile or polycarbonate.

In the embodiment of the carrier medium as carrier stratum, theactivated carbon forms an activated carbon layer, which is preferablyconnected with the carrier stratum via the adhesive, and which abutsdirectly on the carrier stratum. In this connection, a gluing of theactivated carbon layer on the carrier stratum as well as the gluing bymeans of unset adhesive threads applied to the activated carbon can beconsidered. Thus, the carrier stratum defines the activated carbon layerat least on one side and is connected at the same time with theactivated carbon layer.

This embodiment allows the formation of open layers of carrier stratumand activated carbon stratum with immobilized activated carbon layer.Such layers, which are called media layer and comprise a carrier stratumand an activated carbon stratum, can be stacked, wherein thethrough-flow direction is in stack direction, which means orthogonallyto the plane of the layers. In a preferred embodiment, two media layers,which consist each of a carrier stratum and an activated carbon layer,are stacked in such a way that the activated carbon layers of both medialayers abut directly; these two media layers form a stacking unit. Thus,two different activated carbon layers abut directly within an upper anda lower carrier stratum, when stacked. Such stacking units may bestacked further, if required, to obtain a desired total thickness of thefiltering device with a corresponding filtration performance.

A further embodiment features several stacked media layers. Each medialayer consists of a carrier stratum, an activated carbon layer, and aparticle filter layer. An adhesive is introduced into the activatedcarbon layer in order to immobilize the activated carbon particles. Theactivated carbon layer is glued to the associated carrier stratum, withwhich the activated carbon layer forms the media layer, via theadhesive.

The particle filter layer can have a multi-layer design. Furthermore,the particle filter layer can be disposed either upstream or downstreamof the activated carbon layers or also upstream and downstream of theactivated carbon layers.

Two respective media layers are stacked in such a way that the activatedcarbon layers face each other. In this way, a stacking unit of two medialayers is formed, which is defined by a carrier stratum and a particlefilter layer, between which two directly abutting activated carbonlayers are disposed.

In the example of an embodiment according to FIG. 2, the activatedcarbon layers can also be provided with a sealing on their front faces,which means on the width sides and the longitudinal sides. Directlysuperimposed activated carbon layers are advantageously not gluedtogether, the sealing is rather realized only via the directly adjacentcarrier stratum.

Furthermore, it is possible to combine easily different types ofactivated carbon per layer, for example different raw materials such ascoconut, anthracite coal, charcoal or synthetic basic materials,different degrees of activation, different catalytic properties anddifferent impregnations. This allows an adaptation to the target gasspectrum.

According to an alternative embodiment, the activated carbon layer isdefined on both of its lateral surfaces by one carrier stratum; anintermediate activated carbon layer and two carrier strata form onemedia layer. Advantageously, the activated carbon layer is also gluedwith two carrier strata. A media layer or stacking unit consiststherefore of two carrier strata and one intermediate activated carbonlayer, wherein several stacking units may be stacked, if required.

Thanks to a different number of layers or stacking units, great heightswith comparably small lengths and widths of the filtering device canalso be realized, if required. The greater height goes hand in hand withlonger dwell times and a better effective adsorption and leads to alonger service life of the activated carbon filter.

According to a further appropriate embodiment, the activated carbonlayer is sealed at its longitudinal and/or width sides so that togetherwith the carrier strata abutting on the lateral surfaces an all-roundlimitation of the activated carbon layer can be realized, if required.The sealing on the longitudinal and/or width sides enhances thestability and improves the safety against delamination and displacementin the activated carbon layer.

According to a further appropriate embodiment, the carrier medium isdesigned as open-pore foam, for example as a polyurethane foam, in whichthe activated carbon and the adhesive are incorporated. Embodiments canbe considered in which, for the manufacturing of the filtering device,the adhesive is first introduced into the open-pore foam of the carriermedium and subsequently, the activated carbon is introduced. Anotherpossible embodiment is to apply first the adhesive to the activatedcarbon and to introduce the mixture of activated carbon and adhesiveinto the open-pore foam of the carrier medium.

Besides the described folded filter layers, the filtering device canalso be executed with flat filter layers, in particular as wound filter.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and appropriate embodiments can be taken from theclaims, the description of the figures and the drawings. It is shown in:

FIG. 1 a schematic diagram of a first filtering device that featuresactivated carbon as adsorbent, with two stacked media layers, whichconsist each of two carrier strata with intermediate activated carbonlayer; and

FIG. 2 a filtering device with different carrier strata and activatedcarbon layers in another embodiment.

EMBODIMENT(S) OF THE INVENTION

FIG. 1 shows a filtering device 1 for filtering a gaseous medium,wherein via the filtering device 1 a mechanical as well as a chemicalcleaning can be carried out. For example, the air to be supplied to afuel cell can be cleaned via the filtering device 1 from contaminantparticles and from chemical, gaseous substances.

The filtering device 1 features at least two stacked media layers 2,which consist each of two parallel carrier strata 3 and an intermediateactivated carbon layer 4. The carrier strata 3 form each a filterfleece, which is used for particulate removal. The activated carbonlayer 4 acts as adsorbent for the adsorption of volatile matters carriedin the gas flow. The through-flow direction is orthogonal to the planeof the carrier strata 3 or the activated carbon layers 4.

The filter fleece of the carrier strata 3 consists, for example, ofpolyester, polyurethane, polyamide, polyacrylonitrile or polycarbonate.The activated carbon in the activated carbon layer 4 is solidified orimmobilized by means of an adhesive, so that the individual activatedcarbon particles in the activated carbon layer are not able to movefreely, but occupy a permanent place in the stratum. A reactiveadhesive, for example on the basis of polyurethane, or a thermoplasticadhesive, for example on the basis of polyolefins, can be considered asadhesive. The adhesive features adhesive threads, which adhere to thesurface of the activated carbon particles and thus ensure the adhesion.

The activated carbon layer 4 is furthermore bonded with both carrierstrata 3, which is part of the respective media layer 2 and is locatedat the two lateral surfaces of the activated carbon layer 4. On thefront faces, which means on the longitudinal and width sides, theactivated carbon layer 4 can be provided with a sealing, which gives theactivated carbon layer an additional stability and safety againstdelamination and displacement.

The individual media layers 2, which are stacked, may be either looselystacked or also held together by gluing.

Where appropriate, the filtering device 1 may have more than two medialayers 2.

In FIG. 2 is shown another example of an embodiment, in which thefiltering device 1 features also several stacked media layers 2. Eachmedia layer 2 consists of a carrier stratum 3 and an activated carbonlayer 4. An adhesive is introduced into the activated carbon layer 4 inorder to immobilize the activated carbon particles. The activated carbonlayer 4 is glued to the associated carrier stratum 3, with which theactivated carbon layer 4 forms the media layer 2, via the adhesive.

According to FIG. 2, two respective media layers 2 are stacked in such away that the activated carbon layers 4 face each other. In this way, astacking unit of two media layers 2 is formed, which is defined by anupper and a lower carrier stratum 3, between which two directly abuttingactivated carbon layers 4 are disposed. In the example of an embodimentaccording to FIG. 2, two such stacking units with two respective medialayers 2 are stacked. Basically, more than two stacking units can bestacked.

In the example of an embodiment according to FIG. 2, the activatedcarbon layers can also be provided with a sealing on their front faces,which means on the width sides and the longitudinal sides. Directlysuperimposed activated carbon layers 4 are advantageously not gluedtogether, the sealing is rather realized only via the directly adjacentcarrier stratum 3.

Directly superimposed carrier strata 3 of the stacking units can, whereappropriate, be connected with each other, for example by gluing.

According to another example of an embodiment, the filtering device 1features also several stacked media layers 2. Each media layer 2consists of a carrier stratum 3, an activated carbon layer 4, and aparticle filter layer 5. An adhesive is introduced into the activatedcarbon layer 4 in order to immobilize the activated carbon particles.The activated carbon layer 4 is glued to the associated carrier stratum3, with which the activated carbon layer 4 forms the media layer 2, viathe adhesive.

The particle filter layer can have a multi-layer design. Furthermore,the particle filter layer 5 can be disposed either upstream ordownstream of the activated carbon layer 4 or also upstream anddownstream of the activated carbon layer 4.

Two respective media layers 2 are stacked in such a way that theactivated carbon layers 4 face each other. In this way, a stacking unitof two media layers 2 is formed, which is defined by a carrier stratum 3and a particle filter layer 5, between which two directly abuttingactivated carbon layers 4 are disposed.

In the example of an embodiment according to FIG. 2, the activatedcarbon layers can also be provided with a sealing on their front faces,which means on the width sides and the longitudinal sides. Directlysuperimposed activated carbon layers 4 are advantageously not gluedtogether, the sealing is rather realized only via the directly adjacentcarrier stratum 3.

We claim:
 1. A filtering device for the air to be supplied to a fuelcell or for filtering pesticides, comprising: a carrier medium;activated carbon stratum as adsorbent arranged on the carrier medium; anadhesive immobilizing individual particles of the activated carbonstratum together; wherein the adhesive in the activated carbon stratumis a silane reactive adhesive.
 2. The filtering device according toclaim 1, wherein p1 the carrier medium is a filter fleece mediumoperable to remove particulates from air flowing therethrough.
 3. Thefiltering device according to claim 1, wherein the carrier medium isdesigned as carrier stratum; and wherein the activated carbon stratumforms an activated carbon layer arrange on and abutting directly on thecarrier stratum.
 4. The filtering device according to claim 3, wherein asealing material closes over or seals at least one of the longitudinalor width sides of the activated carbon stratum.
 5. The filtering deviceaccording to claim 1, wherein the carrier medium is two carrier medium;wherein each carrier medium is designed as a carrier stratum; whereinthe two carrier medium are spaced apart on opposing sides of theactivated carbon stratum; the activated carbon stratum arranged on andabutting directly onto a first face of it's respective carrier medium;wherein an opposing second face of the it's respective carrier mediumdoes not have an activated carbon stratum secured thereto; wherein theactivated carbon layer abuts onto a respective carrier stratum with itseach of its two lateral surfaces.
 6. The filtering device according toclaim 1, wherein only one lateral surface of the activated carbonstratum abuts on carrier stratum.
 7. The filtering device according toclaim 1, wherein the carrier medium is designed as open-pore foam inwhich the activated carbon and the adhesive are incorporated; whereinthe activated carbon stratum is arranged within the open-pore foam. 8.The filtering device according to claim 1, wherein the carrier medium isa filter fleece medium operable to remove particulates from air flowingtherethrough; wherein the carrier medium is designed as carrier stratum;wherein the activated carbon stratum forms an activated carbon layerarrange on and abutting directly on the carrier stratum; wherein onelateral side of the activated carbon stratum is bonded onto the carriermedium forming a media layer; wherein two of the media layers overlayeach other and are stacked directly abutting on each other with theactivated carbon stratum of the two media layers abutting and directlyadjacent.
 9. The filtering device according to claim 8, wherein abuttingdirectly adjacent activated carbon stratum of the two media layers arenot bonded or glued together.
 10. The filtering device according toclaim 1, wherein the carrier medium is a filter fleece medium operableto remove particulates from air flowing therethrough; wherein thecarrier medium is designed as carrier stratum; wherein the activatedcarbon stratum forms an activated carbon layer arrange on and abuttingdirectly on the carrier stratum; wherein one lateral side of theactivated carbon stratum is bonded onto the carrier medium forming amedia layer; wherein two of the media layers overlay each other and arestacked directly abutting on each other; wherein the activated carbonstratum of a first one of the media layers is arranged on and abuttingagainst a carrier medium of a second media layer; wherein the activatedcarbon stratum of a first one of the media layers is arranged on but notsecured to the second media layer.
 11. A filtering device for the air tobe supplied to a fuel cell or for filtering pesticides, comprising: afirst media layer including a first carrier medium having a first faceand a second face; a first activated carbon stratum arranged on andabutting directly onto the first face of the first carrier medium; anadhesive immobilizing individual particles of the first activated carbonstratum together; wherein the adhesive bonds the first activated carbonstratum onto the first face of the first carrier medium; wherein thesecond face of the first carrier medium does not have an activatedcarbon stratum secured thereto; a second media layer including a secondcarrier medium having a first face and a second face; wherein the secondcarrier medium is spaced apart and separated from the first carriermedium; a second activated carbon stratum arranged on and abuttingdirectly onto the first face of the second carrier medium; an adhesiveimmobilizing individual particles of the second activated carbon stratumtogether; wherein the adhesive bonds the second activated carbon stratumonto the first face of the second carrier medium; wherein the secondface of the second carrier medium does not have an activated carbonstratum secured thereto; wherein the first activated carbon stratum isarranged directly adjacent to and contacting the second activated carbonstratum; wherein the first and second activated carbon stratum areseparate stratum that are not bonded or glued together.
 12. Thefiltering device according to claim 11, wherein at least one of thecarrier medium is a filter fleece medium operable to remove particulatesfrom air flowing therethrough; wherein two of the media layers overlayeach other and are stacked directly abutting on each other with theactivated carbon stratum of the two media layers abutting and directlyadjacent.